Optical imaging, which is one modality of molecular imaging, is a new and emerging discipline that enables mapping in-vivo functions using bio-markers. The bio-markers, introduced into a human or an animal, emits light, either spontaneously or in response to stimulation, which is received by specialized detectors. Since the detectors can gather continuous data, they supply functional information over time. However, a single detector can only supply a two dimensional image, and to determine the 3D location of the process which has taken place, a co-registration, or image fusion, is required. Additionally, since the radiation detected by optical imaging results from diffusive radiation (as opposed to ballistic radiation encountered, for example, in X-rays), it is difficult to reconstruct an image. Therefore, for identifying the location of a desired function, another modality, providing anatomical correlation, such as CT or MRI, is required. The image from the additional modality is then integrated or fused with the data from the optical imager, to form a 3D data set. Furthermore, each modality has its limiting characteristics: an optical imager requires a space which is as sealed to light as possible. An MRI requires an environment which shields it from external magnetic fields, and restricts the use of paramagnetic objects in its vicinity. The surroundings of a CT or nuclear medicine machine have to be shielded from ionizing radiation. Nuclear medicine imaging devices also have to be close to a radiation source.
Prior art shows, that in order to use optical imaging in addition to another modality, the imaged subject is extracted from the optical imager and transferred to another device. For example, US patent application 2006/0258941 to Cable et al, teaches of a subject handling system, comprising a track and a robotic manipulator, which automatically moves the subject between the optical imager and a second imaging system, mainly an MRI.
Other companies providing optical imaging devices offer special containers, in which the subject rests, usually anesthetized. The containers are manually relocated from one modality to the other.
The above solutions require that the subject will be completely immobile between procedures, and that the imaging facilities will be close. However, even under best conditions, the subject might be slightly rotated, or not be properly centered in the imaging device, or even just breathe, which results in anatomical deviation of monitored functions.
Patent application US 2008/0087833 discloses a multi-modality detection system for imaging a region of interest, including a patient organ such as the breast or brain. The region of interest is scanned with a gamma detector and an x-ray detector rotating on a rotatable table, producing SPECT and “micro CT” images. The setting is, however, not compatible for MR imaging because gamma-rays cannot be rotated inside the bore of the magnet, and the electronic components of the machine are harmed by the ionizing radiation. The system disclosed is also not compatible with optical imaging, which requires a setting which is sealed to light. Several disclosures have been made of devices that enable partial or total removal of a receiver coil from within the MRI while the patient remains inside it. For example. U.S. Pat. No. 6,591,128 to Wu et al. discloses an RF coil system with a detachable, relocatable, or interchangeable section. This invention was designed to provide a solution to a different problem with using a separate receiver coil, namely, that its presence within the already-crowded space within the MRI device limits the amount and type of additional instrumentation that can be included in the system. The RF coil system disclosed in the invention of Wu et al. was designed particularly for use in brain imaging, specifically, to allow accommodation of medical devices such as tubes and other therapeutic or life support devices and accommodation for instruments such as probes for functional MRI studies.
U.S. Pat. No. 7,266,406 to Kroeckel discloses another approach to construction of an MRI instrument with a movable receiver coil. This invention discloses an apparatus in which the distance from the receiver coil to the patient's body can be altered via translation of the coil towards or away from the patient's body. The goal of this invention was to provide the increased accuracy of close contact between the receiver coil and the volume probed with the ability to accommodate additional instruments, as well as to reassure the patient by limiting the amount of time spent in the fully constricted space created by the aforementioned close contact between the receiver coil and the patient's body. This invention does not provide any means for moving the receiver coil parallel to the main field axis (i.e. parallel to the plane on which the subject lies during acquisition of the MRI information). Rather, it provides for a plurality of receiver coils positioned along the axis, with the subject physically moved to a particular receiver coil. Of course, having multiple receiver coils adds to the expense and complexity of the MRI system.
A third example of an MRI system with a movable receiver coil is found in U.S. Pat. No. 6,275,722 to Martin et al., which discloses an MRI system with an RF receiver coil that can be swept over the region of interest. The receiver coil in this invention is designed to be swept through a volume of interest within the body of a patient, primarily in order to enable a surgeon to determine whether an operation (e.g. tumor excision) has been successful by enabling accurate MRI of the small volume of tissue in which the operation was performed.
All of these designs suffer from an additional disadvantage that while the best spatial resolution can be obtained when the volume being proved by the receiver coil is located at the midpoint of the MRI's static magnetic field, none of the designs disclosed in the above patents has the ability to place simultaneously the volume being investigated and the receiver coil at that point.
U.S. Pat. No. 6,961,606 to DeSilets et al. discloses a multimodality medical imaging system in which a plurality of tomographic imaging scanners can be used on a single patient. In this apparatus, the patient is translated through the different scanners sequentially. While this device does enable the use of a detached receiver coil for MRI along with any other probe technique desired, it suffers from a different disadvantage. Since the patient is physically moved from one point to another, matching the images produced by the different scanners must be done subsequently, and the matching accuracy necessarily suffers. For example, it may not be possible to determine with certainty whether a feature in an MRI image originates from the same point as a feature in a second image, especially if the size of the feature is small or the signal arising from it is weak.
Pursuant to the prior art, there is therefore a long felt and unmet need for an imaging device and method providing accurate three dimensional images of internal subjects and bodily tissues over time. Furthermore, there is a long felt and unmet need for an imaging device and method accurately providing three dimensional images of internal subjects and bodily tissues over time, the three dimensional images being comprised of NMR derived images and optically derived images. Moreover, there is a long felt and unmet need for an imaging device and method accurately providing three dimensional images of an internal bodily process over time. Lastly, there is a long felt and unmet need for an imaging device and method accurately providing three dimensional images of an internal pathological bodily process over time.